U.S. patent application number 17/701532 was filed with the patent office on 2022-09-29 for cleaning station for cleaning the spraying guns in a spray booth, and method.
The applicant listed for this patent is CEFLA Societa Cooperativa. Invention is credited to Stefano Chiarini, Marco Lombini, Cristian Pungetti.
Application Number | 20220305514 17/701532 |
Document ID | / |
Family ID | 1000006276410 |
Filed Date | 2022-09-29 |
United States Patent
Application |
20220305514 |
Kind Code |
A1 |
Pungetti; Cristian ; et
al. |
September 29, 2022 |
Cleaning station for cleaning the spraying guns in a spray booth,
and method
Abstract
A spray booth for spraying pieces to be painted with a painting
product includes a system that conveys the pieces to be painted
inside the booth, a supplying circuit that supplies a painting
product or solvent to painting tools, a plenum, a mobile wall
providing access to the inside of the spray booth, optionally a
reading system for the pieces to be painted, optionally a filtering
system, a plurality of spraying tools that include one or more a
spray guns each placed on an independent arm moving on a plane and
optionally in a vertical direction, one or more cleaning stations,
placed in correspondence of the mobile wall and provided with a
drawer that is mobile between rest and a cleaning positions and
that includes a painting product or solvent draining tube having a
mouth, a slot for supplying compressed air, and a brush for
brushing the spray guns.
Inventors: |
Pungetti; Cristian; (Imola,
IT) ; Chiarini; Stefano; (Imola, IT) ;
Lombini; Marco; (Imola, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CEFLA Societa Cooperativa |
Imola |
|
IT |
|
|
Family ID: |
1000006276410 |
Appl. No.: |
17/701532 |
Filed: |
March 22, 2022 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B08B 1/002 20130101;
B05B 16/90 20180201; B08B 13/00 20130101; B08B 3/08 20130101; B05B
16/20 20180201 |
International
Class: |
B05B 16/20 20060101
B05B016/20; B08B 1/00 20060101 B08B001/00; B08B 3/08 20060101
B08B003/08; B08B 13/00 20060101 B08B013/00; B05B 16/00 20060101
B05B016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2021 |
IT |
102021000007592 |
Claims
1. A spray booth for spraying pieces to be painted with a painting
product, comprising: a system configured to convey said pieces to
be painted inside side spray booth; a supply circuit configured to
supply a painting product or solvent to painting tools; a plenum; a
mobile wall allowing to access an inside of said spray booth;
optionally a reading system for the pieces to be painted;
optionally a filtering system; a plurality of spraying tools
comprising one or more spray guns, each of the spraying tools being
placed on an independent arm moving on a plane and optionally in a
vertical direction; and one or more cleaning stations placed in
correspondence of said mobile wall, said one or more cleaning
stations being each provided with a drawer that is mobile between a
rest position and a cleaning position, said drawer comprising: a
draining tube of said painting product or solvent provided with a
mouth; a slot configured to supply compressed air; and a brush for
brushing said one or more spray guns.
2. The spray booth according to claim 1, wherein said spraying
tools further comprise a draining gun.
3. The spray booth according to claim 1, wherein said brush is at
least partially immersed in a tank containing solvent, by which
said brush is wetted, said solvent being supplied by the supply
circuit of the painting product or solvent; or wherein said brush
performs a dry brushing of said one or more spray guns.
4. The spray booth according to claim 1, wherein said one or more
cleaning stations are placed on a same side as the spray booth on
which a suction tower is arranged, or alternatively said one or
more cleaning stations are arranged on an operator's side.
5. The spray booth according to claim 1, wherein there are four
spraying tools and four cleaning stations.
6. A method of cleaning spraying tools of a spray booth according
to claim 1, the method comprising the following steps: a. Inserting
the drawer of one of the one or more cleaning station inside the
spray booth; b. Inserting the spraying tool provided with one or
more spray guns inside said drawer; c. Draining the supply circuit
which channels a first painting product by positioning each spray
gun in front of the mouth of the draining tube; d. Optionally,
supplying a solvent to one or more spraying guns, and optionally
positioning each spray gun in front of the mouth of the draining
tube; e. Externally brushing said one or more spray guns by dry
brushing or wet brushing with said brush; f. Externally blowing the
spraying tool with compressed air supplied through said slot; g.
Supplying a new painting product up to the one or more spray guns,
so that the spraying tool is ready to resume painting; h. Removing
the spraying tool from the cleaning drawer; and i. Closing the one
of the one or more cleaning stations with a return of the drawer
into an inside of the one of the one or more the cleaning
stations.
7. The method according to claim 6, wherein the method is performed
with automatic steps, parts of the spraying booth being provided
with actuators under control of a programmable logic controller
(PLC), with which the spray booth is provided.
8. The method according to claim 6, wherein when said spraying tool
is provided with a draining gun, the painting product and the
solvent being first drained with said draining gun.
9. The method according to claim 6, wherein when said brush is at
least partially immersed in a small tank containing the solvent,
the solvent being supplied through the supply circuit supplying an
inside of the one or more spray guns.
10. The method according to claims 6, wherein the pieces to be
painted are sprayed intermittently or in a continuous way.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the technical field of
apparatuses for applying paint on mainly flat pieces such as panels
and/or three-dimensional pieces, known in the art as spray booths.
In particular, the present invention relates to a cleaning station
for the cleaning and the color changing of spraying tools, said
cleaning station being arranged adjacently to said spray booth.
BACKGROUND OF THE INVENTION
[0002] Mainly flat panels are panels, in which two of the three
dimensions are bigger, by an order of magnitude, than the third
dimension. Typically, said panels have measures ranging between
100.times.300.times.18 mm and 1250.times.2400.times.30 mm.
[0003] Three-dimensional pieces are pieces, in which the three
dimensions of a piece are comparable. Indicatively, said
three-dimensional pieces are provided with dimensions ranging
between 200.times.400.times.100 mm and 1300.times.3000.times.200
mm.
[0004] In the art, spray booths are known, which typically are
provided with a closed space (a booth), inside which the pieces to
be painted are conveyed through a conveying system. Typically, said
conveying system comprises at least two rollers, one of which is
usually motorized while the other one is an idle roller, and a
closed belt, on which the pieces to be painted lay. The conveying
system can work so that the pieces are painted while passing (i.e.,
without stopping the closed belt) or intermittently.
[0005] It is worth mentioning that in the present invention said
spray booth works preferably in an intermittent way: a payload
(comprising one to some tens of pieces to be painted) is conveyed
inside the spray booth; the conveying of pieces is stopped; the
pieces are painted, and once the painting is completed, said pieces
are conveyed out of the spray booth. A production batch, painted
with a single painting product (a single color) ranges one payload
to any number of payloads. Typically, the pieces to be painted are
painted in production batches painted with the same color, e.g.,
blue. Subsequently, the spray booth must be cleaned to change
color, e.g., to paint the successive batch with yellow.
Alternatively, the pieces could be painted in continuous, without
stopping the conveying of pieces.
[0006] It is known to provide said spray booths with reading
systems of the pieces to be painted, a plenum, and air filtering
systems. In this context, plenum means a ceiling able to distribute
an airflow entering into the closed space of the booth while
painting takes place. Fans force air into the booth, which can be
adjusted in order to vary the speed and the quantity of air input
into the spray booth in a time unit. The distribution of air must
be as uniform as possible, while the speed of air must be
controlled. In some points of the plenum the airflow can vary,
while it must be constant over time in that specific point. The
adjustment of inlet fans is intended to compensate the pressure
drop, so that the distribution of air to said plenum is maintained
inside optimal pre-set limits. Said plenum is in fluidic connection
with a suction tower arranged on one of the sides of the spray
booth.
[0007] Spray paint application entails that not all the sprayed
paint hits the parts to be painted; the paint not hitting parts
partly hits the conveying system, and partly hovers in the air
inside the spray booth itself. This last portion of sprayed paint
is called overspray, and is partially intercepted by a spray booth
suction system, which can be, in a known way, of different kinds,
and comprise or not a suction tower.
[0008] Finally, it is known to arrange said spray booth inside a
production line, wherein a plurality of machines making different
operation are placed in series upstream and downstream said spray
booth. E.g., upstream said spray booth there may be provided a
machine making a pre-treatment of the pieces to be painted, while
downside said spray booth there may be provided a drying oven
and/or a vertical storage.
[0009] Spray booths are known that through automatic devices
(reciprocators, rotating spraying systems, gantry-robots,
anthropomorphic-robots) spray paint on parts to be painted.
[0010] It is known to provide said spray booths with two spraying
arms, each of which bears at least a spraying tool, e.g., in the
form of known spraying guns. In this context it is worth specifying
that according to the present invention said spraying tools are
preferably Cartesian robots or anthropomorphic robots.
[0011] The current productive system is based on batch-and-queue
production, and generates long lead times; moreover, it requires to
produce panels in advance with respect to shipping. Even with the
more accurate forecast, the emergency production of panels that are
not in the finished goods warehouse is inevitably necessary, or
alternatively obsolescence is generated when such warehouse
inventories are dimensioned so as to have a greater safety
margin.
[0012] All this is antithetic with the most modern techniques for
organizing production, based on methods known as Toyota Production
System (TPS) or Lean Production or Just in Time (JIT). Market
drivers are: delivery speed and product customization, lead time
reduction, reduced dimensions of production batches, developing and
producing special pieces. The production for a more modern
warehouse as performed up to now is possible just for
non-customized product (mass production). The market requirement is
to produce lots size one, with a huge range of finish and
dimensions of the panels, and with pull manufacturing.
[0013] For mechanical processing the problem was tackled, and now
there are provided sundry solutions on the market. For painting,
the problem is more complex.
[0014] The set-up time of the painting machines, although was
reduced to few minutes, inevitably is very expensive due to
material waste and need of cleaning solvents (in addition to the
purchase cost, there is also the disposal cost to be considered).
Therefore, to reduce these costs, the production is scheduled
according to daily shipping, grouping the panels to be produced as
much as possible according to the kind of paint applied. Despite
these methods, the number of paint changes in a working shift went
from about some units to several tens.
[0015] CN111822210A of Fuzhou Zhibuqu Tech CO LTD, WO2019053590A1
of Carlisle Fluid Tech INC, WO2015010018A1 of Graco Minnesota INC
describe cleaning systems for the lumen of tubings and color
changes.
[0016] CN110605208A of Jiangsu Zonghu Coating Equipment Ind Res
Inst CO LTD, DE202012104930U1 of Metso Paper INC, EP300248B2 of Uni
Ram CORP describe cleaning systems for nozzles and spray guns.
[0017] CN106513217A of Shanghai Kafer Automation Equipment CO LTD,
CN111632785A of Hefei Haoming Intelligent Tech CO LTD, CN106362898B
of Qingdao Jinguanghong Intelligent Machinery Electronics CO LTD,
CN107321538A of Shenzhen Taida Robot CO LTD describe automated
cleaning systems.
SUMMARY OF THE INVENTION
[0018] The present invention aims to provide a spray booth allowing
to perform color changing, while minimizing the downtimes due to
color changes.
[0019] This object is achieved by an apparatus and a method having
the features of the independent claims. Advantageous embodiments
and refinements are specified in claims dependent thereon.
[0020] This object is achieved through a spray booth according to
the present invention, which is provided with:
[0021] at least two arms provided with a spraying tool comprising a
plurality of spray guns for applying paint on pieces; and
[0022] at least one, preferably two, cleaning stations of the
spraying tool, which cleaning stations are arranged outside said
spray booth,
[0023] said combination allowing the first spraying tool to be
cleaned while the second spraying tool paints pieces and vice
versa, so that color changing is performed in masked time, without
downtime, i.e., without stopping the painting of pieces.
[0024] Said spray booth is provided with at least one cleaning
station according to the present invention, which is provided with
a substantial box-shape and arranged adjacent to the spray booth.
The arrangement is such that it allows to access the suction tanks.
Said cleaning station comprises:
[0025] a draining tube for collecting paint and solvent. Said
tubing is provided with a mouth; said draining tube drains
paint/solvent in a (not shown) barrel generally placed outside the
cleaning station; said barrel is manually emptied by a human
operator;
[0026] at least a slot supplying compressed air; and
[0027] a cleaning brush.
[0028] Said devices are placed inside a mobile drawer provided with
two positions:
[0029] a rest position, wherein said mobile drawer is inside the
perimeter of the cleaning station;
[0030] a cleaning position, wherein said mobile drawer protrudes in
the spray booth.
[0031] In a first preferred embodiment, the spray booth is provided
with two arms, each carrying a spraying tool, and with two cleaning
stations. In said embodiment, the two said cleaning stations can be
arranged on the same side of the suction tower, or alternatively
they can be arranged on the opposed side, called operator's side,
of the spray booth.
[0032] In a second embodiment, the spray booth is provided with
four arms, each carrying a spraying tool, and with four cleaning
stations.
[0033] The method according to the present invention comprises the
following steps:
[0034] a. Inserting the cleaning station drawer inside the spray
booth;
[0035] b. Inserting the spraying tool provided with spray guns
inside said drawer;
[0036] c. Draining the spray gun supply circuit which channels a
first painting product, by positioning each spray gun in front of
the mouth of the draining tube through an actuator;
[0037] d. Optionally, supplying a solvent to spraying guns, by
positioning each spray gun in front of the mouth of the draining
tube through an actuator;
[0038] e. External brushing of spray guns, in the form of dry
brushing or wet brushing through said brush;
[0039] f. External blowing of the spraying tool through compressed
air supplied through at least a slot;
[0040] g. Supplying a new painting product up to the spray guns;
the spray guns are positioned in front of the draining tube in
order to supply the new painting product up to the nozzle while
they are open to allow the passage from the solvent/old painting
product to the new painting product; the spraying tool is ready to
resume painting;
[0041] h. Leaving of the spraying tool from the cleaning
drawer;
[0042] i. Closing of the cleaning station, with the return of the
drawer into the inside of the cleaning station.
[0043] It is worth specifying that in the case the two successive
painting products are of similar colors and chemically compatible,
e.g., two paints with a similar composition, the first of which is
pale brown and the second dark brown, the step d) with the solvent
can be omitted.
[0044] The first advantage of the present invention is due to the
prevention of downtimes for color changing: this allows to maximize
the working time of the spray booth wherein painting is performed,
with an apparent economical advantage.
[0045] The second advantage of the present invention is the
possibility of working on production batches as small as needed,
and the possibility of using Just In Time production techniques,
while minimizing the quantity of finished products in storage.
[0046] The third advantage of the present invention is that the
cleaning stations are arranged adjacent to the mobile walls with
which typically said spray booths are provided. This allows to use
the cleaning stations according to the present invention even in
spray booths already installed in production lines (retrofit).
[0047] The fourth advantage is that the present spray booth can be
used for intermittent painting or in continuous painting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] Additional advantages and properties of the present
invention are disclosed in the following description, in which
exemplary embodiments of the present invention are explained in
detail on the basis of the drawings:
[0049] FIG. 1 is an axonometric view of a spray booth according to
the invention from the side of the suction tower, provided with two
cleaning stations;
[0050] FIG. 2 is a side view of the spray booth from the operator's
side, provided with two cleaning stations;
[0051] FIGS. 3A, 3B are axonometric views of the cleaning station
separated from the spray booth, the first view being of the closed
cleaning station and with its external housing and the second view
being of the open cleaning station and deprived of its external
housing;
[0052] FIGS. 4A, 4B are a top view and side view of the cleaning
station;
[0053] FIGS. 5A, 5B are a top view and axonometric view of the
spraying tool;
[0054] FIG. 6 is a longitudinal section of the spray booth with the
spraying tools in the positions taken during cleaning;
[0055] FIG. 7 is a side view of the drawer of the cleaning station
during a cleaning operation.
DETAILED DESCRITION OF EMBODIMENTS OF THE INVENTION
[0056] FIG. 1 shows an axonometric view of a typical spray booth
100, in which mainly flat or three-dimensional pieces to be painted
are conveyed through a closed band conveyer 107 (visible in FIG.
6). The bold arrow shows the conveying direction of the pieces to
be painted. A suction tower 112 of known type is provided on the
side visible in FIG. 1
[0057] A spray booth according to the invention is provided with
two cleaning stations 1, 1', the first one being disposed on the
ingress side of the pieces, and the second one on the egress side.
The cleaning stations 1 are mobile, i.e., they can be connected to
and disconnected from the spray booth for maintenance.
[0058] FIG. 2 shows a side view of a spray booth 100 according to
the invention, in which two cleaning stations 1'', 1''' are shown
in their possible working position. FIG. 2 shows the positions of
the cleaning stations 1'', 1''' when said stations are used for
cleaning spraying tools: they are placed on the side opposed to the
suction tower 112, said opposed side being known as the operator's
side. The bold arrow shows the conveying direction of the pieces to
be painted.
[0059] FIGS. 1 and 2 also show the possible positions of the
cleaning stations 1. As can be easily understood from FIGS. 1 and
2, when the cleaning stations 1 and 1' are placed on the same side
as the suction tower, the footprint of the spray booth is reduced.
Vice versa, placing the two cleaning stations 1'', 1''' on the
operator' side provides the human operator with an easier access to
a barrel (not shown) collecting the drained solvent/paint
pertaining to the cleaning station. Being able to place the
cleaning stations on both sides of the spray booth provides the
spray booth with great versatility, which facilitates integration
into any production line.
[0060] It is known in the art to provide spray booths 100 with at
least one mobile, transparent wall 108, which enables access to the
inside of the spray booth. Said cleaning stations 1 are placed in a
position adjacent to said spray booth, with their mobile portion
(see below) placed in correspondence of said mobile wall 108. This
allows providing even spray booth that are already installed in
productive lines with at least one cleaning station according to
the present invention as a retrofit.
[0061] The cleaning station 1 is tied to the spray booth 100 using
fasteners such as screw). Moreover, the cleaning station 1, on the
perimeter that comes into contact with the spray booth 100, is
provided with suitable seals, e.g., made from polythene, which
allow the sealing between said two components and prevents the
dispersion of the overspray into the environment outside of the
spray booth.
[0062] In a first, more common, embodiment, the spray booth is
provided with two arms a spraying tool 10 being provided on each
arm. Therefore, normally just two cleaning stations are provided on
one of the two sides, two cleaning stations on the suction tower
side, or alternatively two cleaning stations on the operator's
side. In a second embodiment, said spray booth can be provided with
four arms, a spraying tool being provided on each arm. Therefore,
four cleaning stations are needed, two on the suction tower side
and two on the operator's side.
[0063] FIGS. 3A, 3B show said cleaning station 1 in two axonometric
views, said cleaning station 1 being shown disassembled from the
spray booth 100. In particular, FIG. 3A shows said cleaning station
1 with its external housing, with a closed cleaning drawer 5, in
its rest position. FIG. 3B shows the same cleaning station 1
deprived of its external housing, with the drawer 5 in its opened
position, defined as the cleaning position. When said drawer 5 is
in its cleaning position, the portion of the drawer 5 protruding
from the cleaning station is placed inside the spray booth 100.
[0064] Said drawer 5 is provided with a mobile protective wall 4,
hinged and blocked with a magnet and a sensor, so that the spray
booth 100 is stopped when the wall 4 is hit by the spraying tool.
This is a safety mechanism: when the spraying tool 110 moves from
its cleaning position toward the inside of the spray booth,
generating a risk of collision, the painting is stopped.
[0065] FIGS. 4A, 4B show said cleaning station 1 with the opened
drawer 5, during one of the cleaning steps which will be explained
below. In particular FIG. 4A shows the cleaning station in a top
view, while FIG. 4B shows the same situation in a side view.
[0066] Said cleaning station 1 comprises:
[0067] A draining tube 6 for collecting painting products and
solvents, provided with a mouth 7; said draining tube drains
painting products/solvents in a (not shown) barrel generally placed
outside the cleaning station. Said barrel is manually emptied by a
human operator;
[0068] At least a slot 8 supplying compressed air;
[0069] A cleaning brush 9.
[0070] Said devices are meant for cleaning the spraying tools 110
with which the spray booth 100 is provided.
[0071] FIGS. 5A, 5B show said spraying tool 110 per se; in
particular FIG. 5A shows a top view while FIG. 5B shows said
spraying tool 110 in an axonometric view.
[0072] Said spraying tool 110 is provided with a supporting
structure on which there are provided:
[0073] Four spray guns 101, 102, 103, 104 provided for painting the
main surfaces of the pieces to be painted;
[0074] A spray gun 105 provided for the edges of the pieces to be
painted;
[0075] An optional draining gun 106, whose function is draining
more rapidly the tubings channeling the painting product/solvent to
the spraying tool 110.
[0076] FIG. 6 shows a longitudinal section of the spray booth 100;
the bold arrow shows the conveying direction of pieces to be
painted (not shown). The Figure shows an idle roller 113 and a
motorized roller 114 which rotate said closed band 107 on which the
pieces to be painted are conveyed. Moreover, the Figure shows the
arrangement of the two spraying tools 110, 110' in correspondence
of the drawers 5, 5' of the cleaning stations 1, 1', respectively.
In this case, the cleaning stations 1, 1' are arranged on the
suction tower 112 side. The two shown positions are the positions
taken by the two spraying tools 110, 110' during cleaning
operations. During painting, the two spraying tools 110, 110' can
take any position that is more central with respect to those shown
in FIG. 6. It is also worth underlying that in the normal working
of the spray booth, only the first spraying tool, e.g., 110, is
painting, while, the second spraying tool 110' is cleaning, and
vice versa. Therefore, the spraying tool 110' is placed in the
cleaning position shown in FIG. 6, while the spraying tool 110 is
free to move over the pieces to be painted, supported by the closed
band 107 for painting.
[0077] It is known that the spraying tools 110, 110' are provided
with four degrees of freedom in their movement:
[0078] A longitudinal direction corresponding to the conveying
direction of the pieces to be painted, thanks to the movement of
arms 60, 60' on which spraying tools 110, 110' are supported;
[0079] A transversal direction, corresponding to the width of the
spray booth 100, wherein the spraying tools 110, 110' move sliding
on their respective arm 60, 60';
[0080] A vertical direction, wherein the spraying tools 110, 110'
come closer/move away to the pieces to be painted;
[0081] Finally, the spraying tools 110, 110' pivot around their
longitudinal axis.
[0082] FIG. 7 shows the inside of the spray booth in a side view.
In the cleaning position, the drawer 5 of the cleaning station is
extracted from the cleaning station 1 as shown in FIG. 4B, while
protruding inside the spray booth 100. The Figure shows the
draining tube 6 in a position adjacent to the spray gun 104; in
particular the mouth of the tube 7 is placed so that it can
collects the fluids (drained paint or solvent) which are drained
from each spray gun 101-106 to be channeled into a (not shown)
barrel.
[0083] In normal working, when one of the spraying tools must be
cleaned e.g., 110, the drawer 5 is moved through its actuator and
brought in its cleaning position wherein it protrudes in the spray
booth, as shown in FIG. 7. The movement of the drawer can occur
only if the arm 60 of the spraying tool is placed outside the
opening area of the drawer 5, and moreover is in an area where
interference with the arm 60' of the second spraying tool 110' is
impossible. Now, firstly the arm 60 of the spraying tool to be
cleaned moves in the conveying direction to approach the drawer 5;
and secondly, the spraying tool 110 moves along its arm 60 to enter
into the open drawer 5.
[0084] The method according to the present invention is applied to
a spray booth 100 comprising preferably two cleaning stations 1, 1'
placed indifferently on the suction tower side (FIG. 1) or on the
operator's side (FIG. 2). It is also possible providing just one
cleaning station 1 which is manually moved toward the ingress or
the egress of the pieces to be painted, according to need. As
already mentioned, the cleaning of one 110 of the two spraying
tools is performed by the cleaning station 1 while the spraying
tool 110' is spraying the pieces to be painted, moving freely
inside the spray booth 100.
[0085] Said method comprises the following steps:
[0086] a. Inserting the drawer 5 of the cleaning station 1 inside
the spray booth 100 (cleaning position);
[0087] b. Inserting the spraying tool 110 provided with spray guns
101, 102, 103, 104, 105 and optionally with a draining gun 106
inside said drawer 5 of the cleaning station 1;
[0088] c. Draining the spray gun supply circuit which channels a
first painting product; Obviously said spraying tools 110 are
supplied by a (not shown) circuit supplying said painting product
to the spraying tool 110, which circuit withdraws said painting
product from a reservoir. In order to supply said spraying tools
100 with solvent, the painting product reservoir must be replaced
with a solvent reservoir; such replacement can be made manually or
automatically, see below;
[0089] d. Optionally, supplying a solvent to spraying guns 101,
102, 103, 104 provided for plane painting and to spraying gun 105
provided for painting edges. The guns 101, 102, 103, 104, 105 are
placed one by one in front to the mouth 7 of the draining tube 6.
In order to place the edge spray gun in front of the draining tube
the tube 6 is to be moved through a pneumatic actuator;
[0090] e. External brushing of spray guns 101, 102, 103, 104, 105,
through said brush 9;
[0091] f. External blowing of the spraying tool 110 through
compressed air supplied through at least a slot 8. This step has
the aim to dry the spraying tool 110 to prevent that drops of
solvent or painting product remained on the outside of the spraying
tool fall on the pieces to be painted;
[0092] g. Supplying a new painting product to spray guns (of a
different color/composition with respect to the previous one) to
spray guns 101, 102, 103, 104, 105. Spray guns are positioned in
front of the mouth 7 of the draining tube 6 in order to supply the
new painting product up to the nozzle while they are open to allow
the passage from the solvent/old painting product to the new
painting product; the spraying tool 110 is ready to resume
painting;
[0093] h. Having the spraying tool 110 leave from the drawer 5 of
the cleaning station 1;
[0094] i. Closing the cleaning station 1., and having the drawer 5
return into the inside of the cleaning station in the rest position
shown in FIG. 3A.
[0095] The draining spray gun 106 is optional. When provided in the
spraying tool 110, the draining steps of the old painting product,
of the solvent and of the new painting product are faster. As spray
gun 106 is not provided with a spraying nozzle, the diameter of the
outlet hole is larger than that of the spraying guns, so as to
allow a bigger flow rate than that of spray guns.
[0096] Supplying the subsequent product pushes the previous product
out from the supplying circuit, for example, supplying the solvent
pushes the old painting product out of the circuit, and the new
painting product pushes the solvent out of the circuit. The changes
are made upstream, manually replacing the supplying reservoir from
which the pump draws, or automatically by using a known system for
changing colors.
[0097] When two subsequent painting products are of similar colors
and are chemically compatible, e.g., two paints have similar
composition, the first one being pale brown and the second one
being dark brown, the step d) with the solvent can be omitted.
[0098] The operation of the brush 9 for cleaning the outside of the
spray guns may be different:
[0099] In a first case, the brush 9 is at least partially immersed
in a small tank containing solvent, from which it is wetted. In
this case, the supply of solvent, which is provided to the small
tank through the same supplying circuit supplying the inside of
spray guns, preferably occurs at a reduced pressure with respect to
the normal supply pressure of the circuit of the painting product
(e.g., 3 atmospheres in lieu of 100 atmospheres);
[0100] In a second case, the brush 9 dry-brushes the spray
guns.
[0101] It should be noted that the cleaning of the outside of the
spray guns is performed just for spray guns 101, 102, 103, 104, 105
and not for the draining gun 106.
[0102] The entire above-described method is automatic: the
opening/closing of the drawer 5, the approaching of the mouth 7 of
the draining tube 6 to one of the spray guns 101-106, the rotation
of the spraying tool 110 to bring each spray gun in correspondence
of the mouth 7, the replacement of the painting product or solvent
to supply the supplying circuit of the spraying tool 110, the
actuation of the brush 9, the supply of compressed air through at
least one s1o6 8, are all performed by specific actuators, placed
under the control of a PLC which is part of the spray booth
100.
[0103] In a completely automatic spray booth, there is provided a
plurality of reservoirs containing different painting products and
a plurality of pumps. When it is necessary to automatically pass to
a different painting product (or to a solvent), changing color
systems are used, i.e., systems provided with valves which can
supply the supplying circuit of the spray booth by selecting from
said plurality of reservoirs placed upstream the control valves.
Such changing color systems are well known in the art.
[0104] As mentioned, the cleaning of one 110' of the two spraying
tools is performed by the cleaning station 1' while the other
spraying tool 110 is spraying the pieces to be painted, freely
moving inside the spray booth 100. At the end of the method steps,
the spraying tool 110 can start the cleaning steps according to the
above-specified method, while the spraying tool 110' can start
painting the subsequent payload of pieces to be painted. Basically,
the cleaning operation on the first of the spraying tools 110, 110'
occurs at the same time as the painting operation by the second
spraying tool 110', 110. Consequently, no downtime is needed to
clean the spraying tools, which occurs in masked time.
[0105] This way, the hourly productivity of the spray booth 100 is
maximized, enabling work on production batches as small as needed.
Potentially, every single payload can be painted with a different
color.
LIST OF REFERENCE NUMBERS
[0106] 1 cleaning station [0107] 4 mobile panel [0108] 5 drawer
[0109] 6 draining tube [0110] 7 tube mouth [0111] 8 slot [0112] 9
brush [0113] 60 spraying tool arm [0114] 100 spray booth [0115] 101
spray gun [0116] 102 spray gun [0117] 103 spray gun [0118] 104
spray gun [0119] 105 spray gun [0120] 106 draining gun [0121] 107
closed band conveyor [0122] 108 transparent mobile wall [0123] 110
spraying tool [0124] 112 suction tower [0125] 113 idle roller
[0126] 114 motorized roller
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